1. Field of the Invention
The present invention relates to an electronic apparatus capable of displaying an image stereoscopically observed based on parallax image data for left and right eyes respectively.
2. Description of the Related Art
Mobile telephones capable of connecting to the Internet through a telephone function thereof are coming into widespread use. As is the case for a personal computer, the mobile telephones of this kind are capable of downloading information or sending and receiving an e-mail message having a file attached thereto via the Internet. Many of these mobile telephones are equipped with a relatively large display device for displaying images and capable of displaying images represented by image data that is downloaded or attached to an incoming e-mail message. It is also a practice to equip the mobile telephones with a camera and thereby, making it possible to display a photographed image and transmit the image data thereof by attaching to e-mail.
In recent years, image data representing left and right parallax images have been provided via the Internet, and therefore, mobile telephones for displaying not only 2D images but also stereoscopic 3D images are suggested (e.g., Japanese Patent Application Laid-Open No. 2001-251403). The mobile telephones of this kind have a display device on which settings are changed for displaying the 2D image and the 3D image.
Furthermore, technologies for generating 3D image data representing a stereoscopic image from 2D image data representing an image photographed by a camera have been also developed (e.g., Japanese Patent Application Laid-Open No. 2000-228778). It is desirable that the mobile telephones be compact in size and light in weight. Therefore, because it is impractical to configure such a mobile telephone with two cameras so as to photograph images for left and right eyes respectively, the technologies for generating 3D image data from 2D image data are suitable for the mobile telephone.
Image data is handled as a file, and the file is given a filename composed of a name for identifying an image thereof and an extension for showing a type of image, i.e., a format of image data. The image data is usually compressed and brought back by decompression, a reversal process of compression, into a format suitable for displaying, because the image data is formed with a large amount of data. The compression is usually performed by the JPEG method, and “JPEG” or “JPG” is given as an extension of the filename in this case. The file is written with information of its image size (number of pixels) together with the image data itself. Furthermore, information relating to the copyright such as an author's name is added to a file of image data that is provided through the Internet.
When an image is displayed or image data is attached to an e-mail message, a user can display a list of files and select the image data. However, it is inconvenient to display only the filenames, because the contents of the images representing the image data are difficult to recognize. Because of this, it has been practiced to create image data representing a scale-down image of an original image, from original image data and to display these scale-down images by arranging side by side. The image scaled down in this way is called a thumbnail image. Image data of the thumbnail image is created by extracting pixel data at intervals from the original image data, in other words, by thinning out the original image data. When the thumbnail images are arranged side by side on display, the user can immediately recognize the content of the image represented by each of many image data, and accordingly, this can make the user's selection extremely easier.
As described above, it is possible to attach image data to an e-mail message and transmit it. However, it has not been long since a mobile telephone capable of displaying 3D images were suggested and, therefore, it is rather difficult to say that such mobile telephones are in widespread use. Because of this reason, even if image data representing a 3D image is attached to an e-mail message and transmitted as is the case for image data representing a 2D image, there is no guarantee that a recipient can make use of such an image. It will be a waste of communication cost for an individual user and socially, a waste of public communication service to attach to an email message and send such image data that may not be used at the recipient side. To avoid such a case, the user alone must pay an attention when image data is attached to an e-mail message. As a result, a burden placed on the user becomes heavier.
There exists a system that adds an identical extension to the files without distinguishing between the 2D image data and the 3D image data. In that system, it is impossible to determine from the extension of the filename if the image data is for the 2D image or the 3D image. In this case, it is necessary to determine if the image data is for the 2D image or the 3D image based on the image data itself This way will cause a delay in changing the settings on the display device for displaying between the 2D image and the 3D image and deterioration in processing efficiency.
On top of this, it is also possible that the user changes or deletes the extension of the filename by mistake. In this case, it will be impossible to learn the type of image from the extension of the filename. Therefore, it also becomes necessary to determine the type of image based on the content of the image data, thereby causing deterioration in processing efficiency.